On Sun, 02 Jan 2011 07:41:27 -0800, Larry Jaques
wrote:

On Sun, 02 Jan 2011 07:15:23 -0500, William Bagwell
wrote:

None I have seen is rough enough. The texture its self is plenty deep but a
smooth and rounded texture. The existing grooves are way too far apart to be
useful. Plus all the center baffles need to be rough on both sides.

T1-11 comes in 4, 8, and 12" dado/groove spacing. Put that on the
outside and just run 1/8" x 3/16" deep tablesaw blade grooves at 3/4
or 1" spacing inside, on both sides of the baffles, horizontally.

Hmm, so your suggesting grooves in both directions? More expensive but also
more like natural bark.

Exterior plywood uses phenol-formaldehyde which out gasses far less than the
urea-formaldehyde typically used with interior plywood. Interior plywood is
unsuitable for other reasons. (De-laminates in the presence of bat urine) Plus
bat houses have no floor or bottom and unless intended for extremely cold
climates must have at least one vent. So basically formaldehyde is not a big
concern.

That's what I understand. I helped my neighbor build some a few years
ago but never heard of their occupancy. He painted them, against my
urging, though.

Actually Bat Conservation International now recommends painting the outside of
wooden houses. The inside should not be painted however a few builders
recommend using something to darken the bottom couple of inches of each
partition to prevent light from reflecting up into the house.

Fish and Wildlife Service bathouse building info:
http://www.fws.gov/Asheville/pdfs/beneficialbats.pdf